WO2019179566A1

WO2019179566A1 - Method for monitoring a supply system of a robot

Info

Publication number: WO2019179566A1
Application number: PCT/DE2019/100244
Authority: WO
Inventors: Bastian Hitz
Original assignee: Leoni Kabel Gmbh
Priority date: 2018-03-19
Filing date: 2019-03-18
Publication date: 2019-09-26
Also published as: CN111867787B; DE102018204184A1; EP3768471B1; EP3768471A1; KR20200128147A; KR102358504B1; US11897124B2; US20210001499A1; CN111867787A

Abstract

The invention relates to a method for monitoring a supply system of a robot, which has a robotic arm (1) and a robotic hand (3) movable relative thereto, the supply system having a supply line (7), in particular a hose assembly (9), and having a guide (14, 30) for the supply line (7) and the supply line (7) being guided along the robotic arm (1) in order to supply the robotic hand (3), the supply system also having a number of sensors (20, 22) for monitoring at least one state variable of the supply system, the functional capability of the supply system being inferred from the values for the state variable that are determined by the sensors (20, 22).

Description

description

Method for monitoring a supply system of a robot

The invention relates to a method for monitoring a supply system of a robot which has a robot arm and a robot hand movable therefor, wherein the supply system has a supply cable, in particular a hose package and a guide for the supply cable, which supply the robot hand to the robot arm is guided along.

Due to the relative movement between the robot arm and the robot hand, the supply cable is guided in such a way that compensation movements are permitted. Due to the diverse movements, different mechanical loads are exerted during a particular machining cycle.

An example of a device for guiding a hose package along a robot can be found, for example, in EP 2 956 277 B1. In addition to mechanical loads, the hose package is also exposed to other stresses, such as thermal loads or media influences. Due to the manifold loads, the hose package is typically a wearing part, which is replaced regularly. Based on this, the present invention seeks to increase the reliability of such a hose assembly and its use time to the required exchange. The object is achieved by a method having the features of claim 1. Preferred embodiments are contained in the subclaims. In the method, a number of sensors are provided for monitoring the supply system of a robot for monitoring at least one state variable of the supply system. On the basis of the determined by the at least one sensor values for the respective state variable is concluded that the functionality of the supply system. Conveniently, a statement is made at the same time about a remaining service life remaining.

The particular advantage of this system is the fact that by means of the sensors active monitoring of the current state, in particular associated with a prediction of the remaining life is taken. The supply line, in particular the hose package is therefore no longer replaced at fixed maintenance intervals. The recorded sensor data are expediently stored and provided with a time stamp in order to track developments in the values of the state variables or also the properties of the hose package and to take them into account for the prognosis. Specifically, for example, changes or the degree of increase of changes can be determined by comparison with previous actual values. The sensor data is conveniently collected continuously during operation.

Preferably, the sensor is integrated directly in the supply line, especially in an electrical cable contained therein.

Specifically, the sensor is designed as a bending sensor, which detects in particular the bends of the hose package or of the supply line during the compensation movements. As a bending sensor integrated in the cable, for example, a bending sensor is used, as described in the German application 10 2018 204 173.3 of 19.03.2018 or as described in the German application 10 2018 204 171.7 of 19.03.2018 the applicant. Full reference is made to these two German applications. Their disclosure content is hereby incorporated by reference.

The cable itself is therefore designed as an intelligent cable, which is used to monitor its own state and thus the supply line.

The sensor expediently comprises a cable element integrated in the cable. This is, for example, a vein or a

Wire pair, which is guided in the hose package. In this line element, a sensor signal is fed by means of a suitable feed unit and an answer signal is evaluated by an evaluation unit. The feed unit and evaluation unit are typically arranged on the same side of the cable. The feed unit is integrated, for example, in a plug of the cable or in a supply unit connected thereto. The evaluation unit itself can be integrated into the feed unit or else can be arranged remotely therefrom. In the latter case, the response signal, also referred to as a reflected signal, is transmitted to the evaluation unit.

The response signal is preferably due to a reflection at a "Fehlsteep", which is caused for example by a bend. The propagation of the sensor signal within the line element as well as a reflection of parts of the sensor signal depend on the dielectricity of the line element, which in turn is influenced by the state variables. Altered temperatures, bending radii, external pressures influence the reflected response signal, which is evaluated to determine the respective value of the state variable. For evaluating the response signal / reflected signal component, for example, a transit time measurement is provided, for example in the form of a

Time Domain Reflectometry, TDR (Time Domain Reflectometry). In this case, a measuring pulse is fed into the sensor wires and evaluated the voltage waveform of the reflected signal component or response signal.

As an alternative to a TDR measurement, a measuring method is preferably used, as described in the applicant's international application of 30.10.2017, file number PCT / EP 2017/077828, which is still unpublished at the time of application. Their disclosure content, in particular their claims (with accompanying explanations), are hereby expressly included in the present application. Specifically, reference is made to claims 1, 2, 6, 7 and 12 with the associated embodiments specifically on pages 5/6 and 8/9. In this case, several individual measurements are carried out in the course of a measurement cycle, with one measurement signal being fed from the feed unit into the sensor cores for each individual measurement, and when exceeding a predetermined voltage threshold value (at the feed location) as a result of the reflected signal component Stop signal is generated, wherein a transit time between the input of the measurement signal and the stop signal is determined, and wherein the voltage threshold value between the individual measurements is changed.

Therefore, exactly one stop signal is generated for each individual measurement. A further evaluation of the reflected signal does not take place. Due to the threshold value changed between the individual measurements, different points of disturbance, which thus lead to amplitudes of different magnitudes in the reflection, are detected by the different transit times, in particular also locally resolved.

Due to the large number of individual measurements, the transit times (stop signals) of the reflected components are therefore generally detected at different defined threshold values. In this respect, this method can be regarded as a voltage-discrete time measurement method. The number of individual measurements is preferably more than 10, more preferably more than 20 or even more than 50 and, for example, up to 100 or even more individual measurements. From the multitude of these individual Thus, a large number of stop signals are determined which are distributed over time. The plurality of stop signals in conjunction with the threshold values therefore approximately represent the actual signal course of the injected measurement signal and the reflected components. Conveniently, from these stop signals, the actual signal profile for a fed-in measuring signal reflected at the power end is approximated, for example, by a mathematical curve fit.

A respective individual measurement is preferably terminated on the basis of the measurement principle according to the invention, as soon as a stop signal has been issued. In order to reliably check the line as to whether there are a plurality of identical impurities, each resulting in a reflected portion with a comparable signal amplitude, a measurement dead time is predetermined in a preferred embodiment after a first individual measurement, during which the measuring arrangement is quasi deactivated and not on a stop signal responds. Specifically, it is provided that after a first individual measurement and a detected first stop signal, a second individual measurement is made, in which preferably the same threshold value is set as in the first individual measurement. The measurement dead time, within which no stop signal is detected, is (slightly) greater than the transit time between the start and stop signals detected during the first individual measurement. This avoids the fact that the reflected portion associated with the first stop signal is detected in the second individual measurement. This cycle is preferably repeated several times until no further stop signal is detected. In other words, the test dead time is matched to the transit time of the (first, second, third, etc.) stop signal detected in the preceding individual measurement, that is to say selected to be slightly larger, until no further stop signal is sent to this set threshold value.

Conveniently, a signal curve is measured by suitably setting the respective test dead time in combination with a variation of the threshold value. In particular, this also detects falling edges in the signal curve. Signal peaks with rising and falling edges can therefore be detected and evaluated. The guide for the hose package generally has a compensation system with a movable guide element. In particular, a hose clamp is often provided, on which the hose package is fixed, and which performs a compensation movement relative to the robot arm. Such a guide element is typically movable against a spring force / restoring force, in particular mounted so as to be movable in a sliding manner. Conveniently, the movement of the hose assembly is now detected and used for the assessment of the functionality of the supply system, in particular the hose package.

Conveniently, the acceleration of the hose assembly, the number of compensating movements, and / or the magnitude of the compensation movement are detected as state variables. Preferably, in addition to the respective current environmental conditions, such as temperature, vibration, etc., recorded and taken into account in parallel. All these state variables are therefore recorded continuously during operation and are included in the assessment of the functionality and in particular in the determination of the remaining service life.

Conveniently, the movement is detected by means of an external sensor, which is arranged in the guide. This can be an electrical sensor, an optical sensor, a proximity sensor or even a pull sensor on a compensation system for the compensation system. In general, an external sensor is preferably arranged in addition to the sensor integrated in the cable. Therefore, sensor data of both the cable-internal sensor and the external sensor are considered and evaluated in order to infer the current functionality of the supply system. In a particularly expedient embodiment, a measured value obtained from the integrated sensor is checked and verified on the basis of the measured value of the external sensor. It is therefore checked whether the data transmitted by the cable-internal sensor are plausible. By this comparison with an external sensor For example, false diagoses are reduced by the cable-internal sensor. Specifically, for example, a bending sensor integrated in the cable sensor and its data are compared with the movement data of the external sensor and verified whether the data is plausible.

For the evaluation of the obtained data and measured values, these are preferably compared with a comparison system and based on this comparison a statement about the functionality is made. Within the comparison system empirical values are stored, for example in tabular form, so that current state information is derived by comparison with the comparison system.

Alternatively, the comparison system is a mathematical model, which thus simulates the real system and describes it mathematically as a function of the variable state variables.

The comparison system is expediently integrated in an evaluation unit to which the measurement data are transmitted. This evaluation unit is integrated, for example, in the machine control for the robot. Alternatively, however, it may also be contained in a higher-level control center or also in an organizational unit not belonging to the operator of the robot. For example, the data contained by the sensors is transmitted to the manufacturer of the hose package, which thus monitors the functionality of the supply system in the sense of a service.

In an expedient embodiment, the state variables are detected in a plurality of supply systems and transmitted to these higher-level, common and thus central evaluation point and evaluation unit. The collected data is then used for a modification of the comparison system. This allows a continuous optimization and further development of the comparison system in order to improve the accuracy of the information. In addition to the internal sensor and the external sensor, at least one further external data source, such as, for example, the machine control of the robot, itself is also used and taken into account for assessing the functionality. For example, motion data can also be derived therefrom on the basis of the control commands, and / or the measured data from the sensors are subjected to a plausibility check.

According to a further, independent aspect, a method for monitoring an electrical system is provided, wherein the electrical system is a data and / or supply system in which at least two components are connected to one another via a cable system. This electrical system in turn has a number of sensors, via which at least one and preferably a plurality of state variables of the electrical system and / or the environment are detected. In this case, the cable system has a cable with a sensor integrated therein and furthermore an additional external sensor is provided outside the cable system. A measured value of this external sensor is then evaluated in addition to the sensor integrated in the cable in order to infer the current functionality of the supply system. As already explained in connection with the robot, both an internal sensor and an external sensor are therefore used to check the operability and also to predict the remaining service life. The external sensor is expediently used in particular for the validation and plausibility check of the data transmitted by the internal sensor.

The electrical system claimed here in general is, for example, a (high-voltage) supply system of a motor vehicle, especially a motor vehicle operated with an electric traction motor. The electrical system consists for example of a battery, a cable and a power electronics / traction motor, the battery is connected via the cable to the drive motor. Alternatively, the electrical system is a car interchange system, for example rail-bound vehicles. It can also be a charging system for electromobility, where the first component is a charging station and the second component is the battery. In general, the inclusion of signals and information from other external sensors improves the quality of the monitoring system based on a sensor integrated into an intreg cable.

An embodiment of the invention will be explained in more detail below with reference to the single FIGURE. This shows a simplified view of a side view of an industrial robot.

In the figure, an articulated robot is shown as a robot. This articulated arm robot 1 is, for example, a multiaxial industrial robot, in particular a six-axis industrial robot. This has a base 8, a first also referred to as rocker 4 segment, which is connected to the base 8 via a first hinge connection R1. Around this first articulation R1, the rocker 4 is about a horizontal axis

pivotable. In addition, the rocker 4 is usually pivotable about a vertical axis relative to the base 8. The rocker 4 extends approximately vertically upwards. At a second articulated connection R2, a second segment, generally referred to as a robot arm 2, is pivotably connected to the rocker 4 about a so-called "axle 3". Finally, as the third segment, a robot hand 3 is connected to the second segment 2 via a third articulated connection R3. Finally, a machining tool 6, such as a welding tongs, etc., is attached to the robot hand 3. Such an industrial robot 1 has a total of six different degrees of freedom of movement. To supply the machining tool 6 with electricity and / or fluids and / or data signals, the industrial robot 1 has a supply line, which is referred to below as the supply line package 7. This is guided along the robot arm 2 and connected from there to the base 8. In the area of the robot arm 2, the supply line package 7 is guided at least in a section in a protective tube. The supply line package 7 together with the protective tube is also referred to below as the tube package 9. Frequently, a separation point for the supply line package 7 is arranged in the region of the second articulated connection and the hose assembly 9 is guided as an exchangeable wear unit up to this separation point.

As can be seen from FIG. 1, a pulling movement is exerted on the hose package during a rotational movement about the third joint axis R3. In the reverse movement back to the starting position shown in FIG. The hose package must be pulled back to the starting position.

For this purpose, in the region of the second articulated connection R2 on the robot arm 2, a device 10 for guiding and retrieving the hose assembly 9 is fastened. In Fig. 1 this is shown only greatly simplified. To this device 10 is a mounting bracket 14 belonging, in which the hose assembly 9 is held, in particular form-fitting, so that a force exerted by the device restoring force is transmitted to the hose assembly 9. The fastening clamp 14 is in particular displaceable against the spring force of a restoring spring (longitudinally). In operation, this therefore performs movements with the hose package.

At its front, the robot hand 3 oriented end of the hose package 9 is additionally fixed by a further mounting bracket 30. The individual lines or the supply line package 7 exits the protective tube at these positions.

In order now to check the functionality of the supply line package and especially of the hose package 9, the hose package 9 has an integrated line element 20, which forms an integrated sensor. This line element extends in the direction of the hose package. This line element is used specifically for detecting bends of the hose package 9. In addition, an external sensor 22 is furthermore arranged, which is arranged especially in the region of the device 10 and, in particular, detects the movements of the compensation mechanism, for example the movement of the fastening clip 4. For example, tensile forces, acceleration values, speed values, number of compensatory movements, etc. are recorded here. Both the data of the sensor 20 and that of the sensor 22 are transmitted to an evaluation unit 24 and evaluated there in order to deduce the functionality of the hose package in particular. For this purpose, a comparison system is preferably contained within the evaluation unit 24 as an image of the real system. The obtained measurement data of the two sensors 20, 22 are compared with the aid of the comparison system and from this a current state information and, in particular, a prediction about the remaining service life is obtained - hit. During operation, the relevant data, for example the movement data, is continuously recorded using the external sensor 22. This data is processed and provided with the time stamp. The data is then compared and correlated with further information, for example with those of the internal sensor 20 or also with other external information, for example from the machine control. Based on this correlation and analysis of the different signals from the different sources of information, especially in comparison with the comparison system, current state data are output with the respective lifetime predictions. The evaluation unit can be integrated in the machine control or alternatively arranged remotely. The signals are transmitted, for example, wirelessly.

According to one embodiment, when the data is acquired, critical states which, for example, exceed a critical limit value are detected and stored as inadmissible states. An advantage of the system described here is that it is also suitable for retrofitting to existing systems.

Particularly in the context of a global approach, the data are collected and evaluated together in a variety of systems used and used in the sense of a learning approach for improving the evaluation, especially the comparison system. The (mathematical) model that forms the comparison system, for example, can thus be continuously improved. In this case, further error messages from the individual installed systems and their failures can be taken into account. In addition to the higher-level central evaluation unit, an evaluation unit is expediently provided for each system, in which the comparison system is stored. This can then be updated centrally.

Claims

claims

1. A method for monitoring a supply system of a robot which has a robot arm and a robot hand movable thereon, wherein the supply system has a supply line, in particular a hose package and a guide for the supply line and the supply line for supplying the robot hand on The supply system further comprises a number of sensors for monitoring at least one state variable of the supply system, wherein conclusions are drawn from the values of the state variables determined by the sensors for the functionality of the supply system.

2. The method of claim 1, wherein the versor strand comprises an electrical cable and the sensor is integrated in the electrical cable.

3. The method of claim 1 or 2, wherein the sensor is formed as a bending sensor.

4. The method of claim 2 or 3, wherein the sensor is formed by a line element of the cable, in which a sensor signal is fed and a response signal is evaluated.

5. The method according to claim 4

wherein in the course of a measuring cycle several individual measurements are performed, wherein

- the measurement signal is fed into the line element per individual measurement,

when a predetermined threshold value is exceeded as a result of the reflected measurement signal component, a stop signal is generated and the individual measurement is terminated in particular,

- A running time between the input of the measuring signal and the stop signal is determined, and - Preferably, the threshold value between the individual measurements is changed.

6. The method of claim 5, wherein after detection of a first stop signal in a first individual measurement, a second individual measurement is carried out with preferably the same threshold value as in the first individual measurement, a measurement dead time being specified in the second individual measurement which is greater than the transit time for the first stop signal detected during the first individual measurement, so that the reflected component associated with the first stop signal is not detected in the second individual measurement.

7. The method according to any one of claims 1 to 6, wherein the guide comprises a compensation system which is connected to the supply line, wherein the movement of the supply line is detected and used for the assessment of the functionality of the supply system.

8. Method according to claim 7, in which, optionally or in combination, the acceleration of the supply line, the number of compensating movements or the magnitude of the deflection is detected.

9. The method of claim 7 or 8, wherein the movement is detected by means of an external sensor, which is arranged in or on the guide.

10. The method according to any one of claims 2 to 8, wherein in addition to the in

Cable integrated sensor an external sensor is located outside the cable and a reading from the external sensor is evaluated in addition to the sensor integrated in the cable to indicate the current functioning of the power supply system.

11. The method of claim 10, wherein on the basis of the measured value of the external sensor, a measured value obtained by the integrated sensor is classified as OK or not.

12. The method according to any one of claims 1 to 11, wherein the determined

Measured values for the state variables are compared with a comparison system and from this a statement about the functionality is made.

13. The method of claim 12, wherein the state variables of a plurality of supply systems detected, transmitted to a higher common central evaluation point and used for a modification of the comparison system.

14. The method according to any one of claims 1 to 13, wherein for the assessment of the operability at least one further data source, such. a machine control of the robot, used and taken into account.

15. A method for monitoring an electrical system, namely a data and / or supply system, wherein at least two components are interconnected via a cable system, wherein the electrical system comprises a number of sensors, on the at least one and preferably several state variables the electrical system or the environment are detected, the cable system having a cable with a sensor integrated therein and an additional external sensor outside the

Cable system is provided, wherein a measured value of the external sensor is evaluated in addition to the sensor integrated in the cable to close the current functioning of the supply system.